A Wisconsin appellate court ruled Thursday that Armslist, an online classified ad site specializing in firearms, can be sued in connection with a 2012 mass shooting at a Brookfield, Wisconsin, beauty salon.

The court rejected arguments that the federal Communications Decency Act limitation on liability for sites hosting third-party content prevented the suit. The lawsuit hinges on site design features that allegedly “encouraged” transactions by people barred from buying guns from licensed dealers, not on the contents of third-party posts, the court ruled. The salon shooter, who killed his wife, two of her coworkers, and himself, and injured four other people, wasn’t allowed to buy a gun due to a domestic violence restraining order, but managed to buy one through a listing on the site.

“The complaint cites a report that allegedly concludes that 54% of Armslist.com users selling firearms are willing to sell to a person they believe could not pass a background check, and 67% of private online sellers in Wisconsin are willing to sell to a person they believe could not pass a background check,” according to the ruling.

The decision comes shortly after President Donald Trump signed a controversial anti-sex-trafficking bill that led Craigslist to pull its personals listings amid fears of liability for sex trafficking and prostitution. Backpage, another classified site widely used by sex workers, was also recently shut down amid claims it facilitated human trafficking.